Hi,
   I understand your concern.
   Last time you had 
abortion in 2nd month of 
pregnancy. Abortions in early months of pregnancy are mostly due to 
hormonal deficiency ( Hormone Progesteron)which causes the pregnancy to be weak & abortion takes place.
   Now you are pregnant again, You must have done investigations after abortion. 
  * - You should consult a gynecologist, show all the previous reports/ get few fresh ones done if so advised.
   - such patients are usually supplimented with hormone Progesteron ( injectable or oral ) It is continued without a break till 3.5 months.
   - continue with other vitamin supplimentsincluding 
folic acid,
   - Take rest/avoid physical or psychological 
stress./ minimum travelling.
   - Be positive
  These precaustions should continue your pregnancy normally.
 * Back ache here may come from calcium deficiency/ weak fetus tending to abort/ pelvic inflammations.The cause is investigated & treated specifically,
 * In pregnancy digestion is hampered due to pregnancy hormones. The solution lies in taking multiple small servings of food- intake of nutritious food ,& use of digestive enzymes as per your doctor's advise