mmm I got really sick once when I wrestled in high school. I was out for two weeks and lost like... 6 pounds. Crazy stuff really. But once I was back in school, I was back on the mat. I had shaky muscles then too. It feels like you go from strength to like... rubber limbs, right?
I couldn't tell you how I got over it. But it does go away. If the strep was really bad and took a lot out of you, your body could still be recovering. If you coughed a lot, it definitely takes energy out of you and stresses your whole body.
Your body just needs to catch up. You can go to the gym still, but maybe don't work as hard as you once could. Drop your workload in the gym by like.. 10-20% and give it another week or so.