Talk to ENT on Underweight/sinus Problem

i am 25 years old my weight is 42kg and height 5ft i calculated my BMI to wo underweight aya hai milk nahi pee sakti me stomach bht khrb hota hai ya to vomit hojati hai and i am hostler physically bhi me bht skinny hu 1 sal pehle mene apna thyroid test karwaya tha wo negative aya tha or mjhe sinus problem bhi hai nasal polyps hen jiski waja se meri nose blocked rehti hai nasal spray (xolisan) use kru to sans ati hai nahi to phr se block hojati 3 years se me isi spray ki waja se sans le rhi hu otherwise nose bht stuffy and full block hojati hai or sans nai ati jiski waja se sans lene m ghutan hoti hai so what should i do now?