I am experiencing mouth sores, painful cracks at the corners of mouth, painful swollen joints (better by: anti-inflammatory medication, rest) (side...

Behçet's disease: It could be Behcet's. This is an autoimmune process that causes mucosal lesions and muscle/joint pain. Please see your primary care provider for an evaluation or referral to Rheumatology.

Various causes: Some causes of persistent or recurrent mouth sores and cheilosis(cracks at corners of mouth) include vitamin deficiency, autoimmune disease, drooling, fungal infection. Your physician or a rheumatologist can evaluate you and order appropriate tests. An oral surgeon or an oral pathology clinic at a dental school may also be helpful in investigating your oral problems.