What Causes Severe Constipation Along With Hard Stools?

i have real bad constapation to the point where i have had to push hard or even tear my bottom, to finally go. then my poop ilooks like rocks put together. when i ve gone no, 2 i still feel like i have somemore that might be blocking it from me going. i have tried Clear lax up to 5 days and it works alittle but i know i feel blocked and after i eat again i go through it over and over . but thid time i gained about 10 pounds over 1-2 weeks making me feel so uncomfortable. My eatings habits were the same. I did cut down on cheese my favorite and pasta. I am 52 , i wwas 130 now within the past 2 months ive gained 20 pounds. Never have i gained for my eating habits. I ride bike daily and use to walk atleast 10 miles aday now i ride bike vigoresly. pls help if u can THANK YOU IN ADVANCE,