Minecraft is glitchy

When I start PvPing, Idk why, but I can't shift click, like, I can shift click once then when I keep holding shift and clicking, it doesn't hit and it starts to lag and gives a sticky keys beep. Another bug is that whenever I move my mouse will pressing w, it will stay in on direction, and it will lock on, give a sticky keys beep, and it won't respond for another minute. Minecraft's running at a really good fps, but Idk why this is happening