My three-year-old Beagle, Russell just recently has been acting weird, he will barely drink water, he has trouble peeing, he acts like he is a lot of pain. When he walks he arches his back like a cat would, and he walks with a limp. I've given him IBprofons to ease his pain but he is slowly getting worse. He has been acting like this for about five or six days. I don't know if it is lethal for him to act like this or temporary. Someone help.

Get him to the vet asap. And also you shouldn't give your pet pills unless your vet tells you its OK

Do you know why he might be acting like this?

I agree he needs vet attention asap... do not want to alarm you but it sounds a lot like distemper. But that is just a hunch from the symptoms you described.

It could be a lot of things, we really cannot tell you, you need a vet to examine the dog.

To me it sounds like it could be a rip roaring urinary infection, but that is only a guess.
Take a urine sample in when you book your vet appointment.

Trouble peeing, back arched (pain?), walking funny, not drinking much.

Urinary tract problem,. Infection? Usually no problem peeing. Badder stone plugging urethra partially?. Hurts, trouble peeing, bladder distending and building pressure which further lodges any urethral plug. Also causes a backup of urine up to and including the kidney/s. This is a serious problem and requires immediate attention, to relieve the pressure if nothing else.
Kidney stone? Pees OK, PAIN, usually in only 1 kidney so other takes up the 'slack' and dog eliminates essentially normally.
There's 3 choices. I'd opt to eliminate the worst problem first, which is a plugged urethra.
Find a vet and GO, before the bladder ruptures and things start downhill. STOP WITH THE Ibuprophen.