My cat is lethargic and wont eat or drink much. He has a dry nose as well. When we pick him up he mewls. He is usually very active, but right now its like he can barely move and has no energy. What is wrong?

I'm sorry, no way to say what's wrong, only that something is, the symptoms don't indicate any one thing. They will need to do an exam and talk to you about everything before there are any ideas as to what might be the cause of the symptoms. Any number of things may have happened, an illness or an injury from a car or a dog or something or just about anything. Have you noticed any changes in your kitty's breath and the way it smells or anything, that can sometimes indicate a poisoning or other internal problems. If he's having problems urinating he may have a urinary blockage or something. It could be so many things.
Your only option to get things started tonight would be to go to the emergency clinic or to see if your clinic has a vet on call. If not, they will refer you to the emergency clinic usually. If things get worse you may want to consider it. I'm sorry, it's a horrible feeling when they are hurting and you can't immediately make it all better for them. I would probably avoid jostling him or picking him up and things until you know what the problem is.  I hope your baby is okay and feeling better soon. Please let us know.