How do I know if I have perforated my ear drum?

Last night my ear was hurting really badly. I could tell it was full of fluid, because I couldn't hear too well. I put some heat on it and took some pain meds. This morning, I have no pain, but it's still full of fluid, and now it is crackling when i swallow. REALLY annoying, but not painful. If I burp or hiccup, THAT hurts. I'm on a z-pack (Zithromax), so there really isn't much a doc could do for me right now, but I'd like to know for my own peace of mind.