need expert opinion re my page

ok, so there's this page that i'm trying to rank for a medium comp keyword. i built some backlinks to it using a service in bhw, and it went from nowhere to #66 in the serps - and back to nowhere.

so i've read phpbuilt's resource on on-page seo, and he said that if you do a search using the exact title of the page and you're not #1 in the serps, you're overoptimized. i did just that and there it is, the page on #1 position in google.

so i think it might be the links.

the thing is, i used the same provider for another page but this time targeting 3 different kws for the same page. the one above only uses one kw. and that page is in the first page of google now. here it is in an easier to read format:

page A:
medium comp kw, built backlinks using same provider, using only 1 kw, appears #1 in G for exact title of article (clean onpage seo), nowhere in serps for target kw after linkbuilding

page B:
medium comp kw, built backlinks using same provider, using 3 kws, now sitting in 1st, 2nd, and 3rd pages for related kws.

so it cant be the backlinks, can it?
i've been reading this forum a lot but this is something i don't understand. please point me in the right direction. thanks.

Hello , please me too i want an expert opinion about my website , can i have some help