hi julia,
the only way you will stop being uncertain is to ask him where you stand with him. just tell him something along the lines of "look, i really like you, but i'm a little confused as to how you feel about me". i would be too if a guy bought me a christmas present, took me out for valentines day, spoke to me so frequently then the calls started to dwindle....and it's for these reasons that i wouldn't hesitate for one moment in asking him what's going on.
the worst that can happen is that he won't want the same thing as you. but if that's the case, then it's actually a good thing because it will allow you to move on with your life and you won't feel confused anymore. there's absolutely nothing to be embarrassed about either.
you'll find the courage to ask him. don't be afraid. if you feel uncomfortable or nervous, just picture him on the toilet with his pants around his ankles having a tough time after eating too much mcdonalds