Possible Withdrawals??

Hello everyone. I have a weird question to ask. For a few months now I have been taking methadone 10mg 4 times a day and have had no problems whatsoever. Well this last RX I have had filled seems to be doing nothing. I feel like I am withdrawls. Is it possible for this to happen?? I dont see any recalls on methadone. I dont want to take more, this is my last prescription of this because in 2 weeks I am going on suboxone. I have looked up methadone for hours on the internet trying to find any information on why this is happening. Could it all be in my head?? I am having the Restless Legs, the back pain, the upset stomach, the severe anxiety. I was wondering if anybody else has had this happen?? I have always gotten the same brand of methadone so I dont know what else it could be. Thank you.

Thanks for the response soccorgirl, I had some old pills left from my last prescription in a purse pill case and it's the same number and maker. My neighbor told me about these pills coming from other countries and they're messing around with prescription pills especially narcotics and that alot of people beleive its some kind of terrosist attack, which I kinda beleive. It scares the heck out of me. I hope that IF this is true that I havent come across one of these meds.
Also I woke up with a sore throat on sunday morning and by monday night I had a very high fever and was in severe pain so I had to go to the ER where they reated me wonderfully and now 2 days later I'm much better, not completely, but mostly. I wonder if maybe me coming down with this bad virus maybe made my body act like it was having withdrawals with actually I was just terribly sick. They ER did give me liquid hydrocodone eventhough I was taking methadone, the doctor felt sorry that I wouldnt barely swallow anything, so he told me to take it if the methadone wasnt covering this strepthroat pain. I havent taken it, the smell of it makes me gag lol.