Hlp! should i and can i call child services?

i know a lady shes 28 shes divorced and has a 7 year old hes obese for sure she doesnt take care of him she never showers him or cleans him he eats more then a grown up she leaves him with her mother which is also dirty and has a 9 year old also obese that has opened wound viruses on his legs! im not sure what they are but they all live in a one bedroom house with a dog! so this lady the 28 year old is never with her son the 7 year old and she often does drugs! i feel horrible for these kids am i overeacting please be honest can i call child services?? how/