4 month sleep regression?

Does this sound like the 4 month sleep regression? LO has been only waking up once a night for a few weeks and then last weekend it progressively started getting worse. Last night it was every hour and a half! During the day, his naps are maybe 30 minutes, and he's super cranky. I really miss my happy baby and my sleep! He also got his four month shots last Wednesday. When he's nursing, he's been falling asleep like he did when he was a newborn and then when I try to pull him off he screams like he's starving. Ugh! How long will this last?!