Thanks for asking at healthcare magic I read your question and I understand your concern Ulcerative colitis is remitting and relapsing disease.. and nearly one half of patients with extensive ulcerative colitis undergo surgery despite therapy.. As it is an immune mediated disease, therapy is targeted to suppress immune system. Humaira injections are the best immunosuppressant as compared to other... While suppressing immunity, the patient become susceptible to infections. Frequency, urgency and joint pain which your son is complaining of is because of urinary tract infection... I would suggest you to have his urine detailed examination followed by urine culture and sensitivity, complete blood counts and erythrocyte sedimentation rate as well as C reactive protein titles... and show these to his health Care practitioner. Take plenty of fluids at least 12 glasses of water per day, take cran berry juice one sachet in one glass of water two times daily. Adopt good hygienic measures... Hope it helps best.. Don t forget to rate this answer and take your best care. Regards Dr Ejaz