yup, see a doctor, possibly a chiropractor. gave yourself some R&R. you can still attend class and watch from the sideline (a different sort of practice - observation practice). or if you do practice, then just walk out from the technique instead of taking the roll to give your body time to heal, but still be able to practice.
Give great consideration toward Ellis Amdur approaches to ukemi. Worked great for me. we called it "monkemi" (monkey ukemi).
Wiped out on my motorcycle last year, the monkemi saved your truly. only issue was my judo reflex swing my arm out for the slap. very bad idea. hands hurt for months, even when I had heavy leather padded gloves on. listen to Amdur about slapping your hands, very very good advice.
Talked to Donovan Waite about ukemi at one of the seminar. he said he no longer advocate the roll over the shoulder like most aikido folks. his forward roll looked like his body goes sideway roll. he also said the purpose of ukemi is to slow your body and dissipate the energy. too many folks tend to throw themselves at the mat. lower your body as far as you can toward the ground before doing the roll.
between Waite and Amdur sensei, they both mentioned that folks tend to roll like wheel instead of ball. Ball is better than wheel; ball can change direction quickly, wheel can't. Ball works great, at least for me.
Took ukemi for Mary Heiny sensei at one seminar and she said I did not come out of the forward ukemi fast enough to come back and attack her. she said there is a way to come out of the forward ukemi very fast, but she could not show me, because of her hips problem. anyone who studied with her that might know about this and can show it in a video of some sort, I'd be eternally grateful. couldn't think of a way to come out fast other than a forward flip with a half pike and 3/4 twist (and served with a piece of lemon).