Ill tortoise

Question
Hi,
Please help me I have a Horsefield tortoise who I look after well and do
everything i was told to do buy the pet shop and vet. He is one and a half but
has been blowing bubbles out of his mouth and nose. He makes noises like
he is  wheezing and has a runny nose. I took him to the vet and she said he
had a cold and gave him an injection. I have also been given antibiotics to
give him daily in a syringe. He isn't eating and Im finding it so hard to make
sure he takes the liquid because he puts his head in. Im afraid im hurting him
when I force his mouth open. I know this sounds stupid but Im so scared he
is going to die. He doesn't eat, drink and Im not sure he is getting enough of
his medicine!
Please tell me how I can make him better or attempt to make him better!
Thank you.  

Answer
Hello KELLIE
Can you tell me please what temps he is staying at? Is the temps hot enough. What is his setting?

Did the vet show you how to propperly administer the  medication?
Opening the jaw is never fun.
What bedding or substrate are you using?
Foods
Does he ever get outdoors?
PLease let me know