It's probably not an issue with the quality of the filament since faults in the filament such as drastic diameter change usually leads to only 'temporary' or sporadic faults in the print. This looks like something happened and its consistent.
My guess is that the filament temperature may have lowered. Lower, but almost sufficient print temp can lead to a zitty appearance as the filament is not as viscous and thus is being more forced out of the nozzle.
Is this a one process print or are the multiple processes? Also, are using all metal nozzles or do they have a PTFE liner in them? If they have the liner, its possibly that it has gone bad.
There are 3 proccesses in this print. The first change over was after about 10mm and it was quite far of the third.
I am using all metal nozels. I think i have discovered now what caused it. I think your suggestion of the temperature lowering was correct. I took the nozzle of to look and there is a small amount of something built up around the thread. I believe this might have caused poor heat transfer between the heated nozzle block and nozzle.
I have since cleaned this up and it seems to be printing fine again.