Remove the shower head from the hose and turn the water on. See if you have good water flow. If you do, clean the shower head as it's clogged with derbies or get a different head for it.
You can replace the hose with something different. More than likely it is attached with a 1/2 inch threaded end, identical to the thread in your house hold kitchen faucet for the cold and hot line. You can get a flexible hose with 1/2 inch threaded ends and get away from the curled up hose. The nice thing is, you can get 1/2 inch nipples (threaded on both ends) and add a second one to make it longer. As long as you can feed the hose back in the wall, you can make it as long as you want.