Bleeding/spotting

I'm spotting on my 15 weeks, then 17-18 weeks, it lasts around 3 days. The doctor recommend me to bedrest, no exercise, and prescribe me with progesterone. Now I'm on my 21 weeks. But as far as i know if you're spotting on really early pregnancy its completely normal, that's implantation bleeding. Consult your gynae immediately if you're bleeding, or spotting with cramps. On my first pregnancy I'm bleeding heavily (like period) on my really early pregnancy turns out i had miscarriage due to chronic cervixitis.