Sometimes the first few periods after a delivery can be heavy. However, as you are on Eltroxin, I suggest you get your TSH tested and make sure the dosage of Eltroxin is correct. If that is OK, then you can take some antiprostaglandin agents like Mefanemic acid 500mg 8 hourly during the heavy menses days. Also, you must get your complete blood counts and peripheral blood smear done. I suggest you take iron and folic acid tablets for at least 3 months- dosage depending upon the haemoglobin level. I assure you will feel pretty normal after this. Also, looking after a newborn is tiring and taxing - and if you do not have good family support that can lead on to depression as well.