Hi, I've Been Feeling A Ticklish Feeling In My Chest

Hi, I've been feeling a ticklish feeling in my chest and also I can't place or hover my hand over my chest without the feeling increasing. I also have shortness of breath at times. I have asthma which occurs after a cold or after exercising. This has been occurring for around a year and I didn't think much of it. However, it has not gone away and has even gotten worse to some degree. What can it be and why is it caused?