Higher kicks

I am really struggling to kick higher. I try to stretch but it feels like my hips have fused and won't let me kick very high! What can I do??? I've just got my red stripe belt and feel this is a real hinderance now.

Try dynamic and static stretching. Its what im doing at the moment and I can see an improvement. Start with leg raises to front and the side of each leg. Then practice a side slowing (holding onto a banister or wall for support) bring knee to the chamber and slowly kick out. You will be using your muscles to keep your leg up and improve them.
Also keep doing your frong and side split stretches too.

Try putting your left leg out and your right leg tucked in and stretch down to the ankle, while keeping your toes pulled back. Also breath out as you do this to allow yourself extra room to stretch down. Then swap legs and do it again. Also try going into a very long walking stance and and then drop the back knee until its two inches off the floor, while keeping your back straight and your hands on your hips. This will limber you up in no time. I hope this helps, Kingy 1st Dan