Senator Dianne Feinstein, who was absent from the Capitol for months after being hospitalized with shingles, suffered serious complications, a spokesperson said Thursday.

The complications included encephalitis and Ramsay Hunt syndrome, a neurological disorder that can arise from the shingles virus. While she recovered from the encephalitis in March, she’s still battling the nerve condition, the spokesperson said.

Feinstein, a California Democrat and the longest-serving female senator, returned to the Capitol last week, navigating the building in a wheelchair and voting for the first time in three months.

“Even though I’ve made significant progress and was able to return to Washington, I’m still experiencing some side effects from the shingles virus,” the senator, who turns 90 in June, said in a statement. “My doctors have advised me to work a lighter schedule as I return to the Senate.”

At the time, her office disclosed that she was still experiencing side effects from the shingles virus that included balance and vision impairments, but the complications were not disclosed until Thursday.

Feinstein has announced she will not seek reelection next year. That hasn’t stopped fellow Democrats, including Representative Ro Khanna of California and Alexandria Ocasio-Cortez of New York, from saying that she should resign because her extended absence prevented the Senate Judiciary Committee from advancing some of President Joe Biden’s judicial nominations.