When you're on immunomodulators and biologics then you should see your doctor upon first signs of an infection like a sinus infection, bronchitis, or a UTI. As your body isn't as capable of fighting it off on it's own. As a consequence, the symptoms might be more severea, appear more quickly, and thus you need treatment sooner (don't and that infection might spread elsewhere in the body causing nasties like sepsis).
You're also on allopurinol (a third immune system suppression med), so i wouldn't delay very long.
Yeah antibiotics suck, but when we've got infections then they're very necessary and we must take them.
It's much better to go to the doctor with a false alarm then let an infection spread within your body. Play it safe and get it checked out asap