Can bicillin l a injection make me drowsy, lightheaded and make my lower back, butt, and leg sore?

Jarisch-Herxheimer?: Benzathine penicillin (Bicillin LA) can cause injection site (buttock) soreness, maybe felt in leg and back on the same side. Bicillin itself won't make you drowsy or lightheaded, but treatment of syphilis (almost the only thing treated with Bicillin) can cause fever, muscle aches, and maybe these symptoms in the first 24 hours ("Jarisch-Herxheimer reaction"). Discuss with the doctor treating you.