My Toddler Has Been Having Wierd Stools For Like 2

My toddler has been having wierd stools for like 2 months or maybe even longer and I went to the Dr 100 times. Finally after negative stool tests I went to GI and he said to take him off of anything sweet for 2 weeks ....so we have been really careful ...just started friday...but I am worried because yesterday I saw that he has a small bruise on his forehead and I don't know of its related or something to worry about because he didn't fall badly or bang his head that I noticed.....I mean he trips a lot but he never hurt himself