Your symptoms of multi-joint inflammation, mild fever, and elevated CRP (18 mg/L) suggest an active inflammatory arthritis, such as reactive arthritis, early rheumatoid arthritis, or psoriatic arthritis. Your current medicine, NAC SR-100 (Aceclofenac), is an NSAID that helps manage pain and swelling but does not cure the underlying condition. You should not self-medicate with alternative drugs. Please consult a rheumatologist promptly for a definitive diagnosis. Depending on the cause, they may recommend alternative NSAIDs (like naproxen), short-term oral corticosteroids, or disease-modifying antirheumatic drugs (DMARDs) to safely and effectively treat the root inflammation.

Severe pain on one side of the mouth, especially while chewing, is usually due to a dental problem such as tooth decay, gum infection, or a wisdom tooth issue. While a pain reliever can help temporarily, it will not treat the root cause. For short-term relief, you can take a painkiller and rinse your mouth with warm salt water while avoiding chewing on that side. However, since the pain is significant and recent, it is very important to see a dentist for proper diagnosis and treatment, which may include cleaning, filling, or other procedures depending on the cause. Do not rely on painkillers for more than a couple of days, and seek urgent care if you develop swelling, fever, or difficulty opening your mouth.