Thanks for the query to H.C.M. Forum.
Let me explain you one thing that control pills , no doubt causes fluid retention in body but very mild.
It was imere coincidence that you took pills and got pain in the joints.
This is a misconception that these pills develops joint pain , however fluid retention can't be denied.
Joints pain as you stated in your query is in knee, toe, lower back pain.
May be due to rheumatoid arthritis
GOUT ( most probable cause as pain is in toe).
Consult an Orthopaedician and get his opinion.
Get in blood for uric acid, Rheumatic factor, C B C , E S R ( chronic infection for osteomyelitis
Lower back pain might be due to pelvic inflammatory disease
and Gynaecologist will help you.
One more misconception is dehydration of joints , you know ,what is meaning of this , if joint dehydrated then , how will you walk.