I vomited last night,but no other symptoms, what could this be?

Last night, after dinner, i was having a sharp pain... i've had the pain many times, and i believe its probably heartburn or an ulcer or something.. but so i took some Tums, and then all of a sudden i threw up... no temperature...didn't feel sick after wards.... and the pain was gone... any ideas? could it be that i just had too much acid in my stomach that was caused by the ulcer thing? or what else could this be? today i feel fine... a little queasy.. and tired... and my sinuses are sort of bothering me... but probably completey unrelated. Thanks!