the site I got my shot on, which is my left side underneath or my neck, underneath my ear all the way to my shoulder cramps up; the site I got my shot on, which is my left side underneath or my neck, underneath my ear all the way to my shoulder cramps up; If I try to use my right hand it cramps and stuff like but If I because I am stretching too far; I am in a lot of pain; its not a cramp its something that you can feel in my neck how it tightens up; I can''t sleep because I tried to lie down and all of a sudden it cramps; yesterday I got the booster Pfizer; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP). The reporter is the patient. A patient (no qualifiers provided) received bnt162b2 (BNT162B2), administration date 20Nov2021 (Batch/Lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (First Dose, original Pfizer shot in Jan), administration date: Jan2021, for Covid-19 immunization; Bnt162b2 (Second Dose), administration date: Feb2021, for Covid-19 immunization. The following information was reported: IMMUNISATION (non-serious) with onset 20Nov2021, outcome "unknown", described as "yesterday I got the booster Pfizer"; MUSCLE SPASMS (non-serious), MUSCLE SPASMS (non-serious), outcome "unknown" and all described as "the site I got my shot on, which is my left side underneath or my neck, underneath my ear all the way to my shoulder cramps up"; MUSCLE SPASMS (non-serious), outcome "unknown", described as "If I try to use my right hand it cramps and stuff like but If I because I am stretching too far"; PAIN (non-serious), outcome "unknown", described as "I am in a lot of pain"; MUSCLE TIGHTNESS (non-serious), outcome "unknown", described as "its not a cramp its something that you can feel in my neck how it tightens up"; INSOMNIA (non-serious), outcome "unknown", described as "I can''t sleep because I tried to lie down and all of a sudden it cramps". Therapeutic measures were taken as a result of muscle spasms, muscle spasms, muscle spasms.  Additional information: Reporter stated, "I had the original Pfizer shot in Jan. I got the second shot in Feb and yesterday I got the booster Pfizer shot you know, everything was fine I went to bed last night. I woke up this morning and the site I got my shot on, which is my left side underneath or my neck, underneath my ear all the way to my shoulder cramps up and that's what woke me up. Once I get the cramp relieved I got to watch how I move before all cramp again its been cramping on and off all day. The only thing that seems to help is putting pressure on it from my hand on the left side, if I try to use my right hand it cramps and stuff like but if I because I am stretching too far I guess, but if I use my left hand I can almost stop it from cramping. My problem is I don't know what to do I have been using Icy-Hot (Intent treatment) but like I have got to get up here in few minutes and use the restroom. I know once I start walking it will cramp before I get to the bathroom in my house and then its I don't know its not really a cramp but it feels almost like a cramp only its very, very painful. So, its not a cramp its something that you can feel in my neck how it tightens up and I don't know, is that a side effect?"  This follow-up is being submitted to notify that the lot/batch number is not available despite the follow-up attempts made. Follow-up attempts completed. No further information is expected.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.