First of all you must feed the baby for 1 year alteast.this good both for you and your baby,I can understand your job problems. What you should be doing is you can express your breast milk before going to work and stored it in refrigerator, so one can give him later whenever he demands,8 months is such an age where one can give many things apart from milk like juices, vegetable soup,baby formula etc.so milk is good but must all the time.Sometime milk intolerance is common if you withdraew for some time and start gradually after It should work fine.

First of all you must feed the baby for one & half yr.this is good both for you and your baby, by breast feeding ur baby`s immunity increase by which he fight with many infections. you can express your breast milk before going to work and stored it in refrigerator, so care taker give him later whenever he demands. at 8 months of age u can give many things other than milk, like juices, vegetable soup, milk baby formula etc. there may be some stomach infection by giving top feed. give anti emetic like drop motinorm 12-15 drops when required & pre & pro biotic like sporlac to him.
if ur baby has all time this type of episode whenever u feed any top milk than there is chance of milk intolerance.if milk intolerance is there than u can`t give cow or other milk. this is conformed by some blood & stool test.