Should I take my Methotrexate injection?

Due to have MTX injection today but have a slight sore throat and have had the sniffles on and off for awhile. Unfortunaltely was around someone with a cold on the weekend. At my ultrasound in February the doctor asked if I had sniffles along with a list of other symptoms. Don't know if he was asking because I have Crohn's or because I am on MTX? I am scheduled for sugery next Monday so will not have that injection anyway. Do people have side effects from stopping? I do not want to get sick and not be able to have the surgery, waited too long. Suggestions?