As a GP, things to call your GPs about post-vaccination
-intense headache with nausea, vomiting, neck stiffness, visual changes.
-severe unable-to-get-out-of-bed type abdominal pain, unable to eat anything
-chest pain and/or shortness of breath
-leg pain with redness and swelling, tender to touch/move
-bleeding (e.g. from gums, back passage)
-tiny dot like spots in clusters called petechiae alongside other symptoms
Generalised aches and pain, lethargy, headache, arm ache in injection site is shit but does go away, usually in a day or so but load up on paracetamol/ibuprofen which will help things.
There was somebody here who mentioned unilateral knee pain which I would have yellow carded because that's not a common reaction, might have been unrelated issue like undiagnosed gout, arthritis or bursitis. In the UK you usually should usually get given a leaflet to take home end of the vaccination and an A4 piece of paper sometimes with common vaccine side effects, which are available on NHS websites anyway. Anything concerning then definitely get in touch. I've not come across a single consult where something major side-effect wise has happened as a result of vaccination which is good considering I do about 7 primary care sessions per week in a busy practice but it does happen.