Is there an effective way to determine if this is an allergy or cold?

Allergy or cold: Cold last about 3 to 5 days, anything longer can be an allergy. Also colds can cause muscle aches and general fatigue and a low grade fever. Allergies don't.

No fever: Allergy is not associated with fever and is not catchy. It may be associated with itching and often responds to antihistamine. In a cold, you tend to get very tired, achy, and feverish. Most colds go away in about a week but allergic diseases will usually linger much longer.