Wait, curiosity has me. What "appendage" did you have removed that causes breathing issues? Sorry, inquiring minds just have to know.
Now to answer your question. I personally, would need a ton more information. The above question, I need to know physical limitations. What does your current workout actually look like? SB is right, you need to get more and better sleep. 5k right too, in general, but for us to help you specifically, more info is needed. What does your diet look like specifically. When I hear,
I don't sleep too much, around 5-6 hours a day, I eat alot and frequently (meat, carbs, vegetables, not many fruits and sweets and sandwiches I try to avoid). I also spend most of my day sitting down, around 14 hours a day sitting.
my red flags go up, I picture this
. I am suspecting, sleep, diet, training and lifestyle issues all need to be addressed. Not trying to be mean, I am trying to be honest in answering your question. We really need more info to better be able to help.