Hello Doctor,
I was pregnant with twin gestation one was about 7 weeks and another about 5 weeks. But I had a miscarriage on 16th June 2012 and doctor said due to infection it had happened but it won't affect next pregnancy and asked to try for a baby after 3 to 4 months and asked to take MCBM 69 Folic acid tablet. From then we are trying for baby but still no result.
On 24th December 2012 consulted another gyno she said there is no problem and asked to take following tablet.
ChromiNAC-A tablet daily twice
FOLITAB daily once
And Fertyl tablet on my second day of periods to 6th day.
From past 3 months my periods are not regular, I usually have my periods between date 16-20 every month, and mostly on 17th or 18th. But now 1st period happened on 20th, second on 22nd and this month on 15th. And I am bleeding only for 1st day and second day just a spotting and 3rd day nothing. Yesterday night we were in contact.
Please tell me why I am having irregular periods?

First of all, miscarriage is common and I would wonder about whether you had an infection. It is difficult to do studies of early miscarriages but there are theories that they are far more common than many women even know about, because they can just seem like a heavy period.
The pill with chromium in it is just a nutritional supplement with an emphasis on chromium. I myself would not take it. There is NO scientific evidence that chromium is even needed by humans, and I myself would not take any metal for which there is no good solid science. Just a good vitamin with all the B vitamins, as well as all the other vitamins and minerals. I am not a doctor!
There are many, many factors involved in fertility and carrying a baby to term. Rather than spend a lot of money on different doctors, be healthy, study online to make sure your diet covers all the protein, vitamin and minerals you need, take multi-vitamins, and try to get pregnant for 3 years. Go for testing if you still don't get pregnant. If you have a miscarriage go for more testing before 3 years. But even 2 miscarriages are common before finally getting pregnant.