Xbox One achievements are glitched/not unlocking.

So last week I was playing a game and randomly two achievements for a different game which I had earned the previous day unlocked and ever since then my achievements have been all messed up. First thing was ALL of my Xbox One earned achievements disappeared
(3 years worth) and I managed to get those to reappear thanks to the forum responding to a question I posted on Friday and I thought that was the end of it. Well turns out it's not because I've since had friends get credit for unlocking an achievement to which
I had unlocked during the previous "glitched" week and lo and behold I didn't receive credit. To test this I fulfilled an achievement requirement on a different game and the achievement failed to unlock! Would love any advice for a fix as I've tried doing
the suggestions under the troubleshooting section (power cycling, cache clear, delete/recover profile etc) and nothing seems to be working.

Additionally I've somehow managed to get a 3250 gamerscore earned (I believe this to be somehow to be a duplication bug because it's for games that I had earned previously and they all say unlocked last week which is false as some of them were earned years
ago I.E All my Destiny 2 achievements reunlocked this week yet I started playing day one launch) for the December month when I view the tab that tracks your per month earnings on Xbox which is NOT accurate and should be in the 100-150 range if I recall correctly
from the last time I viewed it before this started happening. Again any suggestions for a fix are welcome.

TLDR

My achievements are bugged and so far I can't get them working please assist.

:)