WHAT IS THE NEXT STEP AFTER INJUECTABLE FERTILITY DRUGS?

I had taken 3 rounds of Clomid. 150mg last month. I didn't have any major follicles at the doctor last Monday. I can try one more month of Clomid and then my doctor wants me to go on injectable drugs. Has anyone used these? Are the success rates high? I also have PCOS. Also what are the options after injections, if they don't work?