Baby less drink milk

Anak saya sudah 4 bulan dan diberi FM. Tetapi sejak kebelakangan ini sudah mula kurang minum susu. Ada kala minum, ada kala minum sikit saja. Macam mana ye, minta pandangan? My daughter is 4 months now and on FM. BUT Lately I notice she less taking milk. Sometimes, even rejecting it. Please advise