Strep Causing Severe Depression and anxiety

hi, my name is dave. At the age of 15 during my drivers training classes i suddenly got an onset of the crazy depression that i wasnt familiar with at all. My mom and i went through so much things to try to get myself feeling better, but nothing seemed to be working. I am a normal kid and am not struggling with any illness besides this random one. I seem to be normal and back to my self for a good 4 to 7 months and then at any random time it hits me, and im out for 2 weeks with the worst depression anyone can ever imagin, but i try to stay strong. something i was reading onyour websight said that infction can somtimes cause depression. and that is the route we are going now. everytime i have strep throat high in my blood i seem to get very depressed and anxious. i am now 18 years old and getting my tonsils out in a few days to stop the infection mainly to treat the anxiety and depression. Do you think it is possible that this strep throat is causing the Depression. This sickness is ruining my life excpecialy when it counts which is right now in college and i have missed my exam and missed other fun things due to this horrible sickness. please tell me if this is the reason. I NEED HELP!!!!