i am not a doctor, but i would agree with your friend that it sounds like withdrawls!! i am so sorry you are going through this, but hang in there!! if it gets too bad, call your doctor would be my advice. i have never heard of immodium working with withdrawls?!? i have heard of taking a relaxant like valium, etc. to ease the effects. good luck and like i said, hang in there, they should be gone in a few days!!
One can develop some physical dependence in as little as 1-2 weeks of continuous use. It won't be as severe as someone that has taken them for years or course, but it can still be unpleasant.
Immodium AD (and some other OTC AD medicines) does have a synthetic opiate in it called Loperamide that is relatively weak acting on the CNS, but still works like most opiates on the GI tract that tends to relieve diarrhea or cause constipation.
So yes it may help some with the physical side-effects of opiate withdrawal but it can't eliminate all of them by any means. Don't overdose trying to completely get rid of withdrawal feelings though - it just can't do that.