I can't tell if I have a cold or allergies?

Sounds like flu (influenza) because of the body aches. You can go ahead and rule out allergies because you have a fever. Allergies don't cause a fever. If it is flu or a cold there isn't much you can do except ride it out. They usually last 7 to 10 days. During that time you can take OTC meds to treat symptoms. Ibuprofen for fever and aches. Drink lots of water, get lots of sleep. Eat some chicken soup. The steam will soothe your throat and moisten your nasal passages. The protein is easily digested and will give your body some fuel to fight the germs. I'll give you a link to an article that explains the difference between the two.

You mention having a "cold" at the same time every year. When is this time of year? I notice when I finally succumbed and turned our central heating on, for a good 2 weeks I felt awfully grotty and snotty in the head department. I was full of phlegm, always coughing and my nose was constantly blocked. I think now my body has become used to the dry air in the house, the symptoms have all gone. I also try to remember a bowl of water on the radiators around the house which helps to keep the air moist. Might not be the problem but perhaps something to consider :o)

This sounds more like a cold than allergies, as allergies don't cause fevers.