If you think that you're suffering from a bad cold you need to be aware of the following:
1. GPs get p!ssed off with people with common colds cluttering up their waiting rooms ;
BUT
2. No cold ever last longer than 10 days. If your symptoms go on longer you're either suffering from
3(a) a secondary infection ; OR
3(b) an allergic reaction.
In either case it really is time to consult your GP.
While you're waiting for 10 days to elapse, this might help:
http://www.nhs.uk/Con.../Pages/Treatment.aspx
Hoping you get better soon ;-)
Chris