Key Fragments stoped to drop.

i've opened my first chest of this mont and I have 2 key shards and all the keys suddenly stoped to drop, I have a streak of 10 or 15 wins with no key shard drop. I already know keys have reduced drop chance with every key you get, but this is my 2nd chest this month and ive not surpassed my chest limit of 4 per month (2nd chest actually). Someone with this problem?