How Can I Treat Severe Leg Pain While Standing Or Walking After Sitting For A While?

Sir age 68 years Approximately I have been suffering from the following health problem while sitting on a chair slowly to sit I f I sit for a long time, no pain nothing if I try to stand legs highly pain if I try to walk legs pain highly with pain if I walk for 4 to 5 minutes very very slowly I come to normal position in the night while sleeping no pain nothing when I woke up to go to bathroom if I try tthankful to youo stand legs highly pain if I try to walk legs pain highly with pain if I walk for 4 to 5 minutes very very slowly because of pain I come to normal position kindly advise me to get rif pain I am ever