THC Alternatives

I've had intense stomach problems for the last 9 months. I havent had an appetite, vomiting is a daily occurrence, bowels are irregular and usually diarrhea and stomach pain is constant. I've been prescribed everything from reglan to bentyl and other drugs recommended for stomach problems. Ive been tested for everything from crohns to irritable bowel and my doctors have found nothing. The only thing that ive found to work is THC. My mother was a hippie and suggested that I try it and yes, it does increase my appetite and suppress all the stomach problems. The problem with this is..i dont want an illegal substance to be the only thing getting me through life. Are there any suggestions, alternatives, medication that mimics what THC does? I'm desperate. This is controlling my life. I literally havent eaten but a tiny bit in over 5 days, weight loss is getting ridiculous...I honestly dont know what to do with myself at this point.