is a physioloical process in which teeth erput out of bone, piercing overlying soft gum tssues. this process is also associated with change in normal microbial flora of oral cavity. teething process leads to some sort of inflammation in gingival tissue attributed to microbes and the process itself...
Now during this process, it is very general for kids to suffer mild fever
, change in bowel habits like sometimes, it is constipation
or at other times may be diarrohea, vomitting, irritating behaviour to just name a few. the change in color of stool is also, one of the problem. But remember these are, of mild nature and limited durations only. if all these, persists beyond and aggravates, seek an opinion from paediatrician. in those cases, it is not related to teething
Also. weight of your baby is within absolutely normal range for his age.