These chord changes confuse me. For the first four bars it alternates between C#7 and D7 every two beats, then the next phrase it's D#7 E7 for 4 bars. So every two beats you're shifting between one dominant 7th and another one a half step higher and they have no notes in common. If you put the two chords together (like C# D E# F# G# A B C for the first phrase) then you get kind of a weird scale (a bebop scale with lowered 2 and 6?) but that still doesn't make much sense. I guess I'm just having trouble seeing how the chords fit together and how to improvise a bassline or melody over them. Can someone clarify or simplify this in any way for me?