Odd symptoms and I'm scared

My name is Laura, I am a healthy (or so I think) 22 year old and I've been having some symptoms lately that are scaring me a lot.  I guess it started out by whenever i'm trying to fall asleep at night I move a lot and whenever I'm trying to get comfortable I sometimes have an itch here and there, but when I go to scratch that itch, I can't find the itch.  So I try to scratch the area that I thought was right and it doesn't relieve the itch.  That started probably 3 months ago.  About 2 months ago I've noticed my tongue not working like it's supposed to.  When I go to speak to someone it's like my tongue is really tight or thick or something and my speech ends up sounding kinda slurred.  Now, about a week ago, my thumb has started twitching uncontrollably off and on but it seems to be getting worse as the days go on.  I can feel that the muscle twitch starts at about the middle of my forearm and it's kind of painful.  I'm really worried.  The only medication that I take is excedrin pm, or some other type of sleeping pill.  I've been pills to help me fall asleep for years now.  Could that be a cause for problems?  I know it's not good for you.  About 2 weeks ago I was also put on Doxycycline Hyclate for a dermatitis issue and i've been taking that twice a day.  I know that these symptoms are neurological and nerves can't be fixed.  My boyfriend thinks I am a hypochondriac, but I do not think these symptoms are something to take lightly.  Please help me.