General query. Prescribed by my doctor?

Few months back i had a spasm in my lower right rib, i thought it might be something related to muscle. But recently i did an usg abdomen due to stomach issues related to nausea and indigestion, it showed 2.8mm polyp in anterior wall of gall bladder, could that spasm be from the gallbladder when the polyp was starting or something? I have been asked to repeat the usg scan next year so to decide what to do. I have few questions.. 1. Is this anything serious? I am anxious about this. 2. Should I change anything in my diet? I mean should i start avoiding fat like milk, paneer etc? 3. Is there a possibility that this will go away on its own? 4. Is this common in my age? (25M)? 5. Should I do the usg scan after 6 months or 1 year as prescribed by my doctor? Please help me. Apart from this i have symptoms like half solid and rest mushy stools sometimes, upper abdomen feels somehow full sometimes, no pain from gallbladder, my Lft and cbc are normal. Please advice.