Chest breathing symptoms and conditions

I took one and only one. Around 10 hours after I took the medicine, it felt like someone was pushing hard on my collar bones. I felt like my 35 lb. son was setting on my chest. Breathing was difficult. It continued for about 7 hours, sometimes better, sometimes not. I will not take it again. I guess I just need to work on a lifestyle change; instead of depending on medication.

I've been on Doxycyclene for 2 weeks now. I was trying to get rid of my acne. I've vomited twice. (The likelihood of this increases when there's very little food in the tum)Before I vomited, I'd feel like I was having a heart attack. A sudden tightness in the chest, breathing became difficult, a depression that felt like the end of the world. All eventually leading up to vomiting. My acne hasn't witnessed much improvement either. Either it doesn't suit me or I haven't been taking it properly.