Feel very sick after taking Methadone?

Sunday I took 10mg of Methadone at about 1 PM, 5mg every 3.5 hours. Then yesterday I took 10mg at about 4 PM then 5mg 3.5 hours after that. I woke up today and I feel awful. I rarely ever take drugs, this was a first. But some symptoms are: Sweating, headache, dehydrated, very hot, woozy when I stand up, not hungry, heartbeat is light, stuffed nose. That's about it. My heartbeat is higher than the 12 beats per minute as some website said could be signs of an overdose. I've laid in bed all day, only drinking water. I just really need suggestions on what to do. I'm 19, 5'11'', 150 pounds if that matters. Please help! I figured I'd be dead already if I overdosed, so maybe I'm just sick?