As the fetal demand grows in mid-trimester due to the rapid growth, there is nutritional deficiency
unless supplemented properly. Your symptoms suggest anemia
along with electrolyte imbalance
. Get a checkup from your doctor to rule out the cause by getting investigated and start taking required treatment. Also, take proper food containing lot of electrolytes, protein and iron. Take rest in left lateral position, around 8-10 hours in the night and 2 hours in the afternoon. Avoid excessive strain and practise breathing exercises. Wish you a safe delivery.