My 19 yo son is having similar issues. Is extremely thin due to weight loss. He is in the 15 percentile for his height. I feel like I am watching him starve to death. He has been ill with anxiety and diagnosed last August with gastroparesis. Severe nausea upon waking and inability to eat much throughout the day. No nausea meds seem to help and has been on too many to list. Toast in the AM is about all he can handle. There are times he can eat at night, but the nausea is back in the morning and he doesn't eat again all day. In August the doctor tested 8 stool samples for giardia, and other parasites, fecal fat, to H-py etc. along with a phelora of bloodwork. No positive results. We did switch doctors after his primary insisted he eat more. That was helpful. His new doctor is suggesting the SIBO test. My son is in good spirits but is unable to work or go to school due to being constantly nauseous and anxiety ridden. I am so sorry to hear of others with similar issues. It is very difficult feeling helpless with a loved one.