I was in a similar situation to you, with my twins born before my eldest was 3.5 years (and another child inbetween). My SPD had me in a wheelchair with the twins and whilst I felt heaps better as soon as they were born, I was still in a lot of pain for a while and still suffer now to a certain extent. My advice to you would be

1) don't do anything about it yet. Your baby is really little now and your hormone levels are high. There is plenty of time for recovery
2) see your physio. All the time and do what they tell you. You will be able to exercise soon, but now is too early
3) swimming. Once you are ready this is a great exercise
4) Keep wearing your pelvis support, so if you have a girdle or stretchy bandage then keep wearing it now.