hi i had gone through your query and understand your concerns. i would come up with two possibilities
1.the first one include;,RHEUMATOID ARTHRITIS;blood test
for elevated ESR
,CRP,ASO tritre and positive RA factor may confirm the diagnosis
2.second possibility is,GOUTY ARTHRITIS, confirm with blood test for elevated SERUM URIC ACID LEVELS.
I hope this is helpful for you, thank you