It’s possible that your severe knee pain and gas issues are related to the medication you might be taking for joint pain, such as Cartigen DN Tablet, which contains anti-inflammatory agents. This medication can sometimes cause gastrointestinal side effects like gas, indigestion, or abdominal discomfort.

• The knee pain when sitting up could be due to osteoarthritis, which this medication aims to treat by helping rebuild cartilage.
• Gas and other digestive symptoms may be side effects of the medication rather than directly connected to the knee pain itself.
• If these side effects persist or worsen, it’s important to discuss them with your orthopedic specialist or rheumatologist, who can adjust your treatment or suggest ways to manage the symptoms.

If you want, I can explain more about how these medications work or suggest ways to reduce gastrointestinal discomfort. Meanwhile, please consult your specialist doctor for a thorough evaluation and personalized advice.To narrow down potential causes, we will need some more information.Please tell me your age and gender.