I had exactly the same problem with Grace........ she absolutely hated baths ..and screamed the house down. I tried everything........
Grace in her own bath, in our bath, on her own , with us, in the morning, at night, cooler water, warmer water, more water, less water etc etc.. in the end I was getting so stressed...........
then when I chatted to one of the HV - she said that something had probably upset Grace on her first birth and everytime she had a bath after that she remembered it... she suggested that I stop bathing Grace for one month (just give her a wash down) .........as babies have short memories and try bathing her again
I didn't think it would work but I have to say that after the one month - we put Grace in her bath and she loved it... laughed and giggled her way through it and does so in each and every bath now..
Grace was 4 months old at this stage....... you might not need to do a whole month as you lo is younger...... worth a try though