Did you enter any self employed health insurance under schedule C? If you couldn't use it all there then the difference goes to schedule A. Self-employed health insurance deduction goes on Form 1040 line 29, as long as the expense is not greater than your net self-employment income. If it does exceed your net self-employment income it gets split automatically. An amount equal to your net self-employment income goes on Form 1040 line 29, and the remainder gets added in to medical expenses on Schedule A.
Did you buy health insurance from the Marketplace exchange? Or have to pay back the subsidy? If you went to an exchange for Health Insurance, and had to pay back some of the subsidy, part of the adjustment will flow to Schedule A.
If you get Social Security benefits the medicare deduction on your SSA-1099 will flow to Schedule A.
To check Medical expenses just start typing Medical in the search box at the top of your return and pick "medical expenses, sch a" from the drop down list. Then click on Jump To at the top of the list.
