First time mum so probably worrying unnecessarily but ds (9 months) is really under the weather with some strange symptoms which may/may not be related? To summarise:
Gone off his milk and food - for 1 week now and getting steadily worse.
Very windy with absolutely toxic farts despite not really eating/drinking.
Biting me but not interested in teething toys, rings, biscuits etc.
Rubbing his eyes even when not tired.
Minor cold-like symptoms (snotty nose and cough).
In general he is not his usual happy self - he cries at the slightest thing and occasionally let's out sharp cries like he's in pain 
I've tried all the usual teething tricks plus the odd dose of Calpol but it doesn't seem to make any difference. He likes being held/cuddled and is sleeping ok but he's getting skinnier by the day and I'm really starting to worry.
Should I take him to the doctor?
Thanks in advance for any advice you can offer.