Pain in upper part and side by his ribs, into the back; Pain in upper part and side by his ribs, into the back; blood clots in the lungs; Breathing was not normal; It felt like in his back, like the muscles were too tight; This is a spontaneous report from a contactable consumer (patient's mother). A 33-year-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE), first dose  via an unspecified route of administration, administered in arm on 17May2021 (late morning or early afternoon) at age of 33-year-old at single dose for COVID-19 immunization. There was no additional vaccines administered on same date of the Pfizer suspect. Medical history included the patient was diagnosed with COVID-19 in May2021, 15 days before the patient received the vaccine, he was doing very well, it was a light case. There were no concomitant medications. There was no prior vaccinations within 4 weeks. After vaccination, the patient was feeling much better afterwards and felt fine. The patient did not think too much of it. As the day went on, it got worse. The patient had a very serious reaction. The patient had a blood clot in the lungs on 18May2021 and was in the hospital. It was very scary. It was referring to the Pfizer COVID 19 vaccine. The patient received it in (withheld). 15 days before the patient received the vaccine, he did have COVID. The patient's doctor recommended it was ok to go back to work and to have the vaccine. The patient had the vaccine on 17May2021 and by 20May2021, he was in the hospital with blood clots in the lungs. The lung doctor was saying that the blood clot came from the vaccine. The patient had to take blood thinners for 3 months and they are concerned about the long term. The patient was in the hospital for 2 days, in (withheld) from 18May2021 to 20May2021. On 20May2021, the reporter brought the patient home. The patient was in so much pain, reporter took him back in the morning of 21May2021. For event blood clot, it had been 2 weeks. The patient went to work and came home on 18May2021 that day early from work, around 5:00 pm, having pain. The patient called the doctor who said to take paracetamol (TYLENOL) and go to bed. By that evening around 10:00 pm, they ended up taking him to the hospital, where they said he had blood clots. His pain was in the upper part and on the side by his ribs, into the back. The reporter thought at first, it was more to the left but patient was in so much pain, she really could not tell. They said the patient had 2 blood clots, one was on each lung, but they were so small. The pain was so severe. They took the patient to the hospital and he was there 2 days. On 20May2021, they released the patient. When they went to get him on 20May2021, reporter noticed that something was wrong. They gave the patient medication, a prescription pain pill. By the morning of 21May2021, around 06:00, they took him back to the hospital. They did blood work and another CT scan, and said there was no change. When they finally got the patient back into the room, they gave him some type of injection to release the pain. The reporter literally had to call another hospital, who told her to call the nurse supervisor. The reporter was outside calling the nurse supervisor for the emergency room. Then, they said that someone would come out. It had to go that far. After that, when they gave the patient the shot, the pain did subside. When it started to ware off, they gave the patient pain medication. On 22May2021, the doctor called to check on the patient. The reporter was concerned they gave the patient the shot too soon. The doctor said that it would take a while for the medication to take effect. It felt like in his back, like the muscles were too tight and the pain was so bad. The reporter had asked about a muscle relaxer and was initially told to wait until 24May2021 but then ordered a muscle relaxer and it did seem to help some what. On 22May2021, the patient started to feel like there was not any pain and his breathing felt normal. Before that (May2021), the patient's breathing was not normal. It all started happening and could not even explain when. The event blood clots in the lungs required a visit to emergency room for twice, the first time, the patient was admitted to hospital. Treatment included pain medication or muscle relaxers, apixaban (ELIQUIS) after the blood clots. The outcome of blood clots in the lungs and muscles were too tight was unknown, the outcome of rest events was resolved on 22May2021.  Information about lot/batch number has been requested.