13 weeks pregnant bitter taste in mouth.

I am 13 weeks pregnant. Since 6 weeks i have horrible bitter taste in my mouth.No matter what I eat, it always leaves a bad taste in my mouth. This makes food really unappealing. I keep eating chewgum all day but still bad taste comes after thag. Most of the time I have to force myself to eat by thinking of my baby. Is there anything I can do to deal with the bad taste? I have heard this will go after first trimester. Anyone experience this ?