I have extremely severe constipation and i'm supposed to go to an amusement park today.. help!?

A few days ago I went off my healthy lifestyle and ate whatever I wanted for 3 days, and by Sunday I was running a fever and I was sick to my stomach. I've been hospitilized for constipation in the past, but I didn't go in because its so embarrassing... I took a laxative but it did nothing, so yesterday i took double the amount to no avail.. I've used a heating pad to try to relieve pain, but it hurts so bad that if I walk for more than 3 minutes I'm on the floor almost crying my eyes out. It feels like my insides are in knots. Is there anything I can do to relieve the pain?