Is this implantation bleeding?

Hello, today is my 22nd day of my cycle.Last friday i had a follicle ultrasound which was the 17 th day of my cycle and i had 3 follicles, one was 2.0 cm and the other 2 was 1.9 cm. The same day i took pregnyl (hcg shot). The doctor asked me how long was the previous cycle which was 38 days and told me that this time will be long too if i don't get pregnant.i am always irregular. This morning when i wiped myself i had some blood on the tissue (it was red) and after an hour or two i wiped again and the colour was like brownish. Could this be implantation bleeding? When can i make a pregnancy test.?Is it ok If i do one tommorrow or the pregnyl can give me a false result? Thank you all