This is one of those things that is individual. Lomotil on a chronic basis is safe. It is a controlled drug, but the abuse potential is extremely small. They add a small amount of atropine to it to make it intolerable to take in mind altering doses.
That said, some people are very sensitive to even small amounts of atropine, and get the characteristic dry mouth, palpitations, and "jitters" from therapeutic doses of lomotil. Imodium has no atropine, so it does not cause those issues. Supposedly, Imodium actively works to increase water absorption, but I am not sure that it is significantly different in that respect.
Lomotil has been around a lot longer than Imodium and was used for many decades for high output ileostomies and chronic diarrhea. Imodium just has a smaller number of side effects and does not require a prescription (at least not any more). It was a prescription omly med for a long, long time, just like many of the drugs we can get OTC now.
So, long story short, don't worry about your use of lomotil. It is fine. Just more hassle for your doctor (schedule V narcotic).
Jan