If it is just a cold, you will need to tough it out as they are generally viral and antibiotics won't do much if anything for them.
If you are running a fever, mainly anything over 101, definitely call your doctor. I've had a multitude of colds over the years while on Remicade, none of them required any treatment other than good old rest and waiting for it to clear up.....do keep an eye on respiratory symptoms though and as I mentioned any sign of a fever.
Good luck, hope you feel better soon!