D5 MMR problem?

Last season I was diamond III at the end, but after I ranked into plat 2 and climbed to diamond 5 I started losing a ridiculously large amount of LP and gain < 10 per game so i could go on a 4 win streak and lose 1 game and be back to square one. i noticed this happened to all my diamond friends. Is there some kind of MMR glitch for diamond 5 players?