A medical report confirmed the suspicion of a kidney problem afflicting the singer and parliament member whose real name is Kyagulanyi Ssentamu, Medard Sseggona told The Associated Press.
Ssentamu, who is being treated at a private facility in the capital, Kampala, also reported that in detention "they squeezed his manhood," he said. "He was suffering pain in the hips."
All efforts were underway to get the papers necessary for Ssentamu to travel abroad for specialized care, the lawyer said.
Ssentamu, through lawyers and colleagues, has alleged severe torture at the hands of security personnel. He has not made any public statement since he was arrested on Aug. 14 in the northwestern town of Arua for his alleged role in an incident in which the presidential motorcade was pelted with stones.
Ssentamu was freed on bail Monday after being charged with treason alongside 32 other suspects. Ssentamu's driver was shot and killed in the aftermath of the incident, allegedly by the security forces. The government says the killing is being investigated.
Ssentamu and others on Thursday will appear before a magistrate who will consider the evidence and decide if the case should go to the High Court for trial.
Since winning a seat in parliament last year Ssentamu has drawn big crowds while campaigning for several opposition candidates who have won election. He is widely seen as a challenge to the long rule of 74-year-old President Yoweri Museveni with his appeal among Uganda's large youth population frustrated by the lack of jobs. His supporters urge him to run for president in 2021.
Like Museveni, Ssentamu was in Arua to campaign in a local election to choose a legislator. The eventual winner, Kassiano Wadri, has also been charged with treason. Wadri was inaugurated on Wednesday.
Two other lawmakers have been similarly charged but are free on bail.
Another lawmaker arrested alongside Ssentamu, Francis Zaake, is hospitalized with injuries his colleagues describe as serious.
The speaker of Uganda's parliament, Rebecca Kadaga, has written to Museveni urging the arrest of alleged perpetrators within the security forces.
In the letter she said that Zaake "remains gravely ill" and Ssentamu "has visible signs of torture and beatings." Unless the accused officers are arrested and presented in court, she warned, "it will be very difficult to conduct government business" in parliament.
Ssentamu's arrest sparked protests in Kampala and elsewhere demanding his release, with scores of people detained, and a social media campaign to #FreeBobiWine was launched. Dozens of top international musicians, including Angelique Kidjo and Chris Martin, signed a letter demanding Ssentamu's release.
Museveni, a U.S. regional security ally who took power by force in 1986, has been elected five times. Although he has campaigned on a record of establishing stability, some worry those gains are being eroded the longer he stays in power.
Museveni is now able to seek re-election in 2021 because parliament passed legislation last year removing a clause in the constitution that had prevented anyone over 75 from holding the presidency. Ssentamu publicly opposed that decision.
Museveni recently accused "unprincipled politicians" of luring youth into rioting.