What Causes Extreme Tiredness With Nausea & Headache?

I had a non MRSA staph infection of the spinal fluid as a result of an infected brain shunt. Now, I am extremeky tired, nauseous, with headaches and pain. My ESR is 92 up from 55 4 weeks ago. rheumatoid tests and blood cultures came back negative. CRP is positive. TEE was negative. any thoughts on what is going on?