You need to contact an orthopedic surgeon for evaluation and investigations. This is likely related to osteoarthritis, though a family history of Lupus does warrants blood work specifically for it. This does not look related to rheumatic disease. The pain extending up to the thigh and groin is due to abnormal weight bearing to protect from pain and thus other muscles and joints in lower limb have been affected. The conservative therapy of the osteoarthritis knee is following:
1) Knee care in the activities of daily living. Few simple self-care measures can be remarkably effective in ending pain cycle.
a) Avoid prolonged standing or walking or sitting with joint in a single position.
b) whenever you sit, keep the knee stretched and fold them intermittently.
c) Squatting, sitting cross legged should not be done.
d) Avoid climbing stairs.
e) Avoid sitting legs unsupported or hanging.
2) Rest: Taking a break from your normal activities reduces repetitive strain on your knee, gives the time to heal and helps prevent further damage.
3) Anti-inflammatory medications
4) Physical therapy; the goal of physical therapy is to strengthen the muscles around your knee and help you regain knee stability. Ideal is supervised physical therapy. Stretching exercises are also part of the physical therapy regime.
5) Orthotics and bracing.
6) Glucosamine and chondroitin orally for about 1-2 years and a trial of diacerin for three months.
7) Hyaluronic acid injections in knee.
8) Local analgesic sprays and ointments to your skin may help relieve the pain and stiffness of osteoarthritis.
9) Deep Electrotherapy by physical therapist. Please see these resources for the exercises (you can pick which suits you best);
Please feel free for your follow up questions.