Blocked milk duct size of golf ball in ?

I have been cutting out one feed at a time over the past 2 months and now down from 9 feeds to two feeds a day for my 18 mth old. However last week I developed a blocked milk duct and a tiny white pimple lookin on one of the holes, that I burst and squeezed out hard cheese like milk. I applyed an anitbiotic cream to it and cleared the lump. One wwk later I again have the lump again this morning in same place, but bigger. I dont seem to be able to mage it out. (No white spot this time). its big, hard and sore. Will it develope into mastisus (i have had mastitus 6 times in past 12 mths)? should I start antibiotics the Doc gave me some in case I get it back again, or will it clear? Does the duct blocked come out of more than one hole cause one of the holes wont drain at all? Its hard when Im trying wean to offer all the time.