If you have a picture, that may help. It does not sound like your regular stuck shed or scale rot when referring to the breakage on the edges. The pieces coming off may just be stuck shed and that of course is a humidity issue. A humidity hide usually does the trick for that.
But the breakage on the edges of the belly scales is concerning. It could be an area where the snake had ticks and were clipped off with possibly twissers or nail clippers. Don't know though. Has the snake defecate yet. Look to see if the urates are coming out green. If so, this can be an indication of internal parasites. Don't get alarmed!!! I am just assuming now. I am not a vet or an expert, but if it's what I think it is; I had a red tail rat snake with a similar sounding problem. Other information that can be helpful is weight of the snake. Is it a normal weight, overweight, or is it underweight. How does the snake's skin feel. Is it smooth or does it feel dry and rough. This is usually an indication of dehydration. Look to see if there are folds in the skins. Is it tight or can you pinch it with significant folding. If the breakage in the belly scales have brownish residue then it could be scale rot. Then the opposite is needed. There maybe to much humidity or was exposed during previous ownership. Without a picture it will be hard for anyone to tell you anything. Post a pic and I bet a lot more people will recognize what it is.