Just got done with a 2 week test prop cycle. I didn't feel stronger until the third week, however, my work capacity increased. That is, my max didn't go up but I was able to do more reps at a given weight than I had previously.
I cut my prop with filtered GSO and filtered my gear as well. I then combined both in a new, sterile vial.
The pain and fevers may be the result of a low grade infection from dirty gear.