A good quality probiotic may help. Starches feed Lyme and Candida and other critters, and if there is already an imbalance, then high starch foods can magnify that imbalance.
Another possibilty is the development of a sensitivity to potatoes. Might discuss allergy testing with your doctor, including the IgG delayed hypersensitivity blood tests. Get tested before you stop eating the food, because the IgG tests are not as accurate if you aren't eating the foods being tested.
Chronic Lyme, Bart., Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut dysmotility & non-specific inflammation, Lupus, Osteoporosis, etc.; G-Tube
Meds: Ceftazidime, Flagyl, Zofran, Domperidone, Claritin, Singulair, Prednisone, herbs, homeopathy, supplements, etc.