wont let me pick up blocks in creative out of my inventory i have to hold down mouse button and drag item

Ok so I can play Minecraft but when im in any gamemode like survival or creative if I click an item it glitches and stays in the same spot but if I hold down the mouse button and drag the item moves.
Its really making me mad and if im in my inventory and I hold shift to put on armor it dosent work.
the bug started yesterday 4-8-15 at approximately 10:00 eastern time.
Any day before 4-8-15 everything was perfectly fine please get back to me as soon as possible.
P.S. my in game name is: Parkour_King