Ok heres what i would do in your situation. Hell this is what i did the other day since im outta morphine right now
Go to the nearest drugstore and get some lopermide for sure because your going to need that stuff bad. The brand name is immodium but get the generic since the name brand shit costs alot more. That is unless you want the liquid (tastes kinda minty and abit gross especially if you puke alot during WD like me) which works faster but you get alot less for your money. That will help the diarehea and maybe the stomach cramps abit too.
If your nauseous or throwing up try to get some OTC anti-nausea meds. I don't know where you live so they might have different things in whatever country your from. Dimenhydrinate aka dramamine aka gravol is a pretty good one.
Save those percs for that trip! Trust me you will be kicking yourself in the ass if you eat all of them now and the weekend comes and you get sick as a dog and can't go on your trip. I can't even make it up the street sometimes when im dopesick so i couldnt imagine sitting in a car for a long time and then going to see a concert. So yeah save the percocets and the tramadol. Tramadol helps some people during withdrawal but others not so much. Whatever you do be very fucking careful mixing the tramadol with anything. Like someone else said read up on that shit.
Good luck to you. Ya sound like you need it.