<s>[INST] I never had PCS growing up. I am a 34 year old male, and started taking a supplement of Glucosamine 1500 mg + MSM 1500 mg (2 tablets is the total dosage) daily. While taking this supplement, I started having sharp chest pains, and didn t know if I was going to die of a heart attack. I did figure out that if I took a deep breath, I would feel a sudden pop, and the pain would go away. I am so glad taking the deep breath worked, because the pain was crazy. This would give me relief for a while, until I got another episode (around a couple a day). After going through this for days, I decided to try and stop taking the supplement, along with the multi-vitamin I was taking, and the PCS completely stopped. I have not had any since I stopped taking them. I just wanted to see if you thought this may be some information that could be used to isolate a certain chemical that may be elevated in some people that may trigger episodes of PCS. Thanks. [/INST] Hello, The only possible reason here for chest pain is a side effect of a supplement of glucosamine and methyl sulfonylmethane (MSM). You should discuss with your doctor regarding change of the molecule. Hope I have answered your query. Let me know if I can assist you further.Regards, Dr. Bhagyesh V. Patel </s>