Count Consecutive months

Hi All,

I was wondering if there is someone who can help me out with something here.

Ok...We have a retail shop and we want to see for each customer if he had bought at least once a month any product consecutively. To see the concept: If he had bought the product let say 2 two times in January-2014, 1 time in February-2014 and 3 times in March-2014 and nothing else after that, I want simply to show 3 (times). Of course, a customer may have bought the product at a later date, let say, 5 months after, but in this case, I will need another count again for him.

Now, the example:

What I have is (below I have transactional data):
CustomID | date of purchase

44444 | 01/01/2013
44444 | 05/02/2013
44444 | 16/02/2013
44444 | 26/03/2013
44444 | 18/05/2014
44444 | 29/06/2014
55555 | 05/09/2013
55555 | 01/10/2013
55555 | 10/10/2014
66666 | 11/11/2012


What I need to show (I need distinct data):

CustomID | 1st_time_of_consecutive_purchases | 2nd_time_of_consecutive_purchases |...the list may go up to 8 times, but for simplicity purposes let see for up to 2 times.
4444 | 3 | 2 |
5555 | 2 | - |
6666 | - | - |


Any ideas how to do it in Excel?