PIP stopped no letter at witts end cant pay bills or buy food please HELP answer if you have any idea

My son diagnosed with autism Over 10 yr ago now and he received his pip monthly and I get carers allowance..for some reason pip stopped I check bank ballance it not been there last 2 months I cant phone as its easterwkend am going of my rocker they're hasling for rent the bills have just gone out am am getting deeper Into max of overdraft with what looks like no way to pay it..I have no family and am on my own and I can't tell my son as it will make him distressed. I have had no letter saying I need to resubmit any forms nothing. THE only thing I can think of is that he has a fixed amount t of yrs and that time is up..but I can't find nor have got any letters from them saying that. At this point I have my eye on a rather fat pigeon should it come to that..