HELP !!

okay so this is my 6th month on birth control. this past week was my last week taking the pills before getting my period & I got it 5 days early. my period blood is extremely dark. it doesn't appear to look like period blood, very thick. last months period was really light, almost like spitting for like 4 days and I usually go on with my period for 7-9 days. should I be concerned/ worried? is having dark period healthy?