Decreased fetal movement in 20 weeks?

i am 20 weeks pregnant, i have been feeling my baby move inside me quiet regularly and frequently since two weeks now. for the last 3-4 days the movement has decreased and there hasn't been a movement (i have not felt it) since yesterday morning (almost 24 hrs). i dont knw if its normal or is it a cause to worry? i have also not been feeling very hungry lately unlike the beginning of my second trimester when i used to feel hungry all the time, now i just feel like having a lot of water and other liquids. this may be because of the extremely hot weather i am in, does it have to do something with the baby kicking? i am a little worried but i dont want to be freaked out just yet. has this happened to anyone else? is this a normal thing to happen? or should i see my doctor asap?