I'll answer your second question first. See your primary care doctor. He or she can ask specific questions about your symptoms, perform a physical exam (including a joint and neurologic exam) and decide on next steps.
Possible causes of your symptoms include:
Leg pain that radiates from the hip area to the lower leg could be due to sciatica. This condition is named after the sciatic nerve, which starts in the lower spine and travels through the buttock into the back of the leg. Branches extend into the lower leg and feet. When this nerve is compressed or irritated, it causes pain that is often felt in the low back or buttock and moves down the back of the leg into the lower leg. Sometimes there is weakness in the leg or foot. The most common cause is a herniated ("slipped") disc in the back. Iliotibial band syndrome
This tough band of tissue connects the front of the pelvis to the outside of the knee. Irritation of this tendon is common among athletes. This is especially true with repetitive motion, as seen in long-distance runners, cyclists, or soldiers during training. This condition more commonly causes knee pain, but it can cause hip pain that radiates along the iliotibial band. Hip bursitis
The bursa is a sac-like structure. It is located over our large joints (including the hips, knees, shoulders, and elbows). The bursa allows the smooth movement of the structures outside of the joint when the joint moves. Inflammation of the bursa (due to repetitive activity, injury or for no identifiable cause) may cause pain on the outside of the hip. This pain may radiate down the outside of the thigh. However, the pain does not usually extend to the knee or ankle. Arthritis
Hip pain for 4 months that's getting worse over time could be due to hip arthritis. However, hip arthritis does not generally radiate to the ankle. Knee arthritis could cause knee pain that radiates toward the hip and ankle. But given your age and more prominent hip pain, this is not the most likely possibility.
Again, see your primary care doctor for an evaluation.
Orthopedists, rheumatologists and physiatrists (specialists in physical medicine and rehabilitation) all see patients with your symptoms. But you may not need to see a specialist.
If the cause of your symptoms is sciatica or iliotibial band syndrome, all you may need is conservative treatment. This might include taking acetaminophen (Tylenol or generic versions) or an anti-inflammatory drug. You might also need physical therapy and a change in your exercise routine.
Other tests and treatment will depend on the cause of your symptoms, any other symptoms you've had (such as fever or weight loss) and your progress with conservative treatment.