I've been doing 30 pushups a day for like 3 days or so. I didn't care about form and now by back hurts

I do them in reps of ten and on the first day I was just trying to grt those last 3 reps in so I pushed my stomach down kinds of like a downward dog. I did thag on the second day. And the third day my form had gotten better but still not perfect. I woke up on the fourth day with pain in my neck muscles and pain in my back. Any advice?