How To Remove Noticeable Veins On Arms?

my arms and upper arms! I also excerise every day for about 30 to 45 min on the tredmill. I use to workout for an hour but now I am running only for 30 min. I can notice it very well in my arms and I am scared of wearing short sleves can you please tell me what to do should I not run any more? My parents and doctor said I am underweight. If I reduce the amount of running will the veins go away! pleae help I am afraid!! Also I am scared that I will gain alot of weight if I stop! My parents say I need aleast 5 pounds! I am 5" 1, 19 years old and my bmi is 16.6.