Hi there... Leg pain with swelling could be because of many causes like muscle strain, tendinitis, undernutrition, electrolyte imbalance(causes muscle cramps), deep vein thrombosis, varicose veins,peripheral arterial diseases, if it's associated with backpain then it could be due to neurological causes like sciatica, sacroilitis.. To treat it finding exact cause is needed. Get mri leg and Doppler of leg once done. Symptomatic treatment like hot fomentation, local application of gels with diclofenac, oral tablets containing aceclofenac/diclofenac, avoid standing for long time, do leg exercises regularly.