Inserting Lines Based On IF

I have an amount of data split into various fields. I need to do something similar to the following:

In each row I have three fields separated by columns: name, sector and specialty. There is only one name and one sector for each record, but possibly several specialties (of which there are fifteen types in total, so they do not appear in a consistent column. specialty 'i' could appear in columns 3, 4, 5 through to 17. ie, sample entries below:

sheet 1
a1 name a2 sector a3 specialty i a4 specialty iv
b2 name b2 sector b3 specialty ii b3 specialty iv b4 specialty x
c3 name c4 sector c5 specialty i c6 specialty ii

The thing is, for every specialty in a row, I need new records created, so the above would become:

sheet 2
a1 name a2 sector a3 specialty i
a1 name a2 sector a3 a4 specialty iv
b2 name b2 sector b3 specialty ii
b2 name b2 sector b3 specialty iv
b2 name b2 sector b4 specialty x
c3 name c4 sector c5 specialty i
c3 name c4 sector c6 specialty ii