It's probably not related to your cold - your glands would be swollen in your neck, not your groin.
Did you happen to pull any muscles? Fall?
Are you hydrated? Alcohol is very dehydrating. Make sure you are drinking enough water, and lay off the alcohol and caffeine.
Since it's been lingering for a few days, you should probably get it checked. Let your doctor know if you've had any possible exposures to STDs, or if you have any pain with urination, defecation, etc.
Let us know what happens, and hope you feel better soon. :)
Can’t be any sti I have had a girlfriend for the last 2 years and both are clean.
I have been hydrated so could be this but am I right in saying that the prostate is there could it be something to do with that?
Yes, it could be the prostate, or a UTI, or a hernia, even. Really, anything along those lines.
You really need to see a doctor to figure it out, since it could be so many different things. Let us know what happens. I'll be interested to hear what this is.
Feel better :)