Search for fiscal quarter and year

I have a spreadsheet that looks at outstanding quarterly data. The current column headings are:

1 - Q4 2007 .... 11 - Q2 2010 12 - Q3 2010 13 - Q4 2010 14 - Q1 2011

The column headings will change as each new quarter is entered, with the new quarter appended to the end, and all previous quarters with no outstanding data removed.

The first column (which is J) will always be fixed, but the last column will depend on the numbers of quarters being shown.

I need to enter a formula to determine all the quarters prior to the current year and quarter. for example, if I have Q4 in cell A1, and this is year 2010, I want to look up in my column headings where Q4 2010 is listed, (in this case it is the heading "13 - Q4 2010"), then sum all the columns from J up to, but not including that one.