What Causes Swelling In Pubic And Suprapubic Region After Workout?

hello ... im 28 years old female , weight nearly 44 kg &150 cm hight . After gym & abdomial exercise I noticed pubic & suprapubic swelling , its generalised soft (like fat or fluid ) ,no discoloration only mild pain in both groins , its in the pikini area .it decreases at morning , ultrasound was normal ..but now The swelling back . before it was flat . what it could be ?