Jenny Mollen says she's now taking medication for the hyperthyroidism that caused her rapid weight loss

Jenny Mollen now knows “for sure” that she has a hyperthyroid condition, which caused her rapid weight loss.

The actress and author, 38, tells PEOPLE that she’s seeing more doctors to confirm her diagnosis, which is likely a form of Graves’ disease, but is now on medication to treat the hormonal condition.

“I’m feeling good,” Mollen said at a spin class Thursday night celebrating Stayfree‘s Free to Be You campaign and the launch of their Ultra Thin pad with All-In-One protection. “I’m on meds. I’m just dealing with it.”

Credit: Ester Segretto

The mother and wife of actor Jason Biggs gave birth to the couple’s second child, Lazlo, in October, and revealed on Instagram on April 13 that she likely had a thyroid condition as a result of her pregnancy.

“Many of you have written and asked me about my rapid weight loss,” Mollen wrote. “Weight loss that to be honest, I couldn’t really explain until now. This morning I woke up w a giant bulge in my neck the size of a golf ball. I had blood work and an ultrasound and will be waiting for the results over the weekend. Though I am not certain, I have good reason to believe it is some sort of hyperthyroidism. Apparently this is common in women AFTER PREGNANCY.”

Mollen adds to PEOPLE that she’s learning more about the condition.

“I guess it’s 1 in 12 women have this happen so I mean it’s kind of crazy statistic,” she says. “I guess it’s more common than you realize.”

Mollen has also learned about a few other conditions that are common after pregnancy but go undiscussed, like bladder leaks.

“My son [Sid, 4] loves these indoor-bouncy-sort-of trampolines — they have a bunch of those back here. I went with him and I was jumping, jumping, jumping and I could feel the pressure but I didn’t think anything was going to happen, and all of a sudden I’m like, ‘Oh my gosh, I literally just peed,'” she says. “I think more people are dealing with this than we even know. I feel like it’s great that Stayfree is trying to normalize the conversation around it, not make it so weird.”

Mollen also noticed that her body changed even more after her second child.

“From your first kid, your body still kind of looks the same once you get back in shape. This time I’m like, things are hanging,” she says. “Things are weird. Everything’s a little just weird. I’m like sort of a Picasso.”

But Mollen tries to be kind to herself.

“I always have things I want to change. I’m like, ‘Oh this, I should do this and that.’ I try to stay positive about it because I’m like, what is the use in being negative about it? What is that going to do?” she says. “I’d rather just be positive about it and then go see a surgeon if I really wanted to change something.”

And she has Biggs on her side to cheer her up.

“He would never say a word [about my body]. He wouldn’t,” Mollen says. “And Jason is weird. Jason, I feel like he is into weird s—. I say that I want to change things, but he’s like, ‘No, everything’s perfect — just leave it as it is.”