HEART NOT PUMPING PROPERLY; VERY SICK; CAN NOT DO ANY LIFTING; LEGS VERY SWOLLEN; VERY ENLARGED HEART; BLOOD CLOT IN LUNGS; PAIN IN STOMACH/TERRIBLE PAIN IN STOMACH; LOW LEVELS OF PLATELETS; SWOLLEN BELLY; WEIGHT GAIN; CHRONIC DIARRHEA; This spontaneous potential legal report received from a patient concerned a 55 year old male. The patient's weight was 215 pounds, and height was not reported. The patient's past medical history included: blood clot in the stomach, and concurrent conditions included: HIV (HIV but has been controlled and gets checked periodically every 3 months), restricted lung function, nonsmoker, and no alcohol use, and other pre-existing medical conditions included: The patient had allergies. The patient had no drug abuse or illicit drug usage. The patient received covid-19 vaccine ad26.cov2.s (Dose number in series: 1) (suspension for injection, route of admin not reported, batch number: 041A21A, expiry: UNKNOWN) dose was not reported, 1 total administered on 08-APR-2021 to right arm for prophylactic vaccination. No concomitant medications were reported. On MAY-2021 (date unspecified), the patient experienced chronic diarrhea (On and off) and had Abx (antibiotic) and diarrhea got a little bit better for 2 weeks, and patient experienced weight gain since vaccination (usual weight was 210-215 pounds), and the patient noticed swollen belly. On JUN-2021 (date unspecified), the patient had blood work and medical doctor said results (Results back in JUL-2021) were showing blood platelets were low which was went from 130000 to 90000. Meantime the patient experienced shortness of breath (different type, not the same as with restricted lung function), and the patient thought it could be covid, and had complained of gasping for air and pain in chest. On SEP-2021, the patient again undergone for blood test and result was found to be 70000. The patient reported, that he had another test, then he was put on prednisone and levels went up to 90000 but then back down to 70000. In the same month (SEP-2021), the patient talked to primary care provider and got a referral for hematologist. Meantime primary care provider suspects blood clot and ordered more test. On OCT-2021 (date unspecified), at the beginning medical doctor said that, the patient was positive for blood clotting as per blood tests and suggested to go to emergency room. Since the patient had no insurance, received treatment on outpatient basis at a non-profit clinic. On NOV-2021 (date unspecified), hematologist said all symptoms were related and the patient experienced legs very swollen and medical doctor said that, patient to go to emergency room otherwise could die in any minute. The patient visited emergency room, as he was concerned about life-threatening symptoms. Emergency room confirmed blood clot in lungs, very enlarged heart and causing swelling of leg. The patient was not admitted in the Hospital, though 3 specialists talked to him explaining seriousness and why he needed to stay. From emergency room the patient patient went home on apixaban (Eliquis) 20mg first week and then 10mg. During emergency room visit in NOV-2021, the patient weighted 225 pounds and went down to 215 pounds after started apixaban (Eliquis) and mentioned that it could be related to water accumulation. The patient reported that, stomach pains and diarrhea could be due to enlarged heart and heart not pumping properly (date unspecified) or a blood clot. On 29-NOV-2021 (Monday), the patient experienced terrible pain in stomach and took 4 ibuprofen, went to bed and woke up fine. On an unspecified date, the patient thought that he had a blood clot in stomach and experienced very sick, can not do any lifting and risk for heart attack. The patient had upcoming appointments for hematologist and cardiologist. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient was recovering from low levels of platelets, legs very swollen, pain in stomach/terrible pain in stomach, and weight gain, had not recovered from very enlarged heart, and chronic diarrhea, and the outcome of blood clot in lungs, swollen belly, very sick, can not do any lifting and heart not pumping properly was not reported. This report was serious (Other Medically Important Condition).; Sender's Comments: V0: 20211209584- COVID-19 VACCINE AD26.COV2.S - blood clot in lungs, low levels of platelets. This event(s) is labeled per regulatory authority and is therefore considered potentially related.