I had asked for a picture of the changes in the mouth and throat and have not received a reply.
The most common cause of the changes in the mouth and throat and the enlarged gland under the chin would be an infection. The most common infection would be a viral
infection, but the appearance on a picture may suggest another infection or a different cause.
A positive FIT screening test indicates that there is some blood in the stool, but does not identify the condition causing the blood or the location within the gut. It can be anywhere from the stomach, such as gastritis or ulcers, to the small or large intestine, such as inflammatory bowel disease, vascular growths, or diverticuli. However, the reason that checking the stool for blood is done as a screening test is that another possible cause of bleeding is cancer of the colon or a polyp in the colon, some of which seem to be pre-cancerous.
The usual response to a positive FIT screening test is to perform additional studies to identify the cause of the bleeding. The most common tests would be a colonoscopy and an endoscopy of the stomach.
If I can provide any further information, please let me know.