Advice please

Every single day I gain 3 or 2lbs like seriously everyday and I don’t lose it either it just all piles on and I can gain over 14lbs in a week but it can be as little as eating something like a banana a day or something and I will gain weight. My stomach will bloat so bad itspainful and makes my clothes not fit me i also don’t go to the bathroom for a number 2 for weeks at a time. What could be wrong