I need advice.

So, alright my main account is VV i n d right? I was plat 1 but slowly dropped all the way to plat 5. That's my bad. But rn I'm on a 15 lose streak on this account. Like for some reason my main account is nearly impossible to win on. So I made another account (Don't know if that's bad) But I got it to plat 5 in like a week from silver 5 skipping teirs. The mmr of that account is High plat, i'd play with plat 2's in gold 1. Still high plat.

So that's what im confused about... my MAIN account that i've had for years and has all my skins and champs I can't win for anything, but my other account I can win no prob... Any adivce for helping this problem out? I don't want to use my other account as my main account because I have barely anything on it lol but at this rate idk.