You might not have had the nipple in the right place. I use a manual but if I don't get the nipple in the middle-ish I end up with bruises. Probs the suction was too strong though, does it have a gentle option to start with?
Hi Dizzyme, I use the lactaline as well and also get dark patches. They fade pretty quick so I assume it is just blood being pulled to the surface, you can try turning the suction down but to be honest I decided that being able to express quicker was worth the odd 'love bite' patch! It doesn't hurt.
I am feeding EBM full time having been unable to get a proper latch, so I spend about 3-4 hours in every 24 on the pump at the moment, have done for the last few months with no serious side effects.