Strep throat is very nasty & if let to 'run its course' can turn into rheumatic fever - one of those 'old-timey' sounding diseases that can permanently ruin your heart. Usually the cankers in strep are on the throat itself, but I'd still go to a doctor.

Gargling w/a weak solution of hydrogen peroxide or warm salt water can clear up minor tonsil/throat infections. You can also make goldenseal tea & use that as a gargle.

Echinacea is only an immune-system booster - once you're sick, it's pretty useless. The best way to use echinacea is when you know it's cold & flu season, everyone in your school or job is sick & you don't want to catch anything - either drink the tea, 1 cup 2X daily (1 tsp. to 1 cup water, steeped, not boiled) or find the higest concentration in a commercial preparation & take that once a day. Only use it for about 2 weeks at a time, & let your body rest for 3 weeks so you don't burn your immune system out.