See a doctor.
It is rare but there have been cases of inflammatory myopathy as a complication post tattoo - it's been found in cases where people are immuno-suppressed - which could be for a number of reasons.
I say "have been cases" - a quick google only brings up one - so it seems very rare - or under-reported.
Not saying that's your issue of course - as above - you should see a medical professional (internet forums are not the best place to get any kind of diagnosis).
"https://www.bmj.com/company/newsroom/beware-of-getting-a-tattoo-if-your-immune-system-isnt-up-to-scratch-doctors-warn/"