So I had an engineered roof truss made for me by a local company for my garage and they are on a 28 foot span with no load bearing walls. The truss has a room built into them that is 14feet wide and the bottom chord is only made of 2x6 with a gusset plate in the middle of the floor span. So now after a year the trusses are droped down in the middle about 3/4" on 28' every one. Any ideas how to fix

How much weight have you put inside that room, was there a greeat deal of snow this past winter? I would definitely contact the builder and complain, ask what is their warranty.3/4" isn't much and that may be all that will happen.