My 2-cents' worth:

"Bollockitis" I can also see interpreted as "Bull$h¡titis".

1) When someone tries to pull a fast one on someone else, the someone-else may counter with an exclamation of "Bull$h¡t!" or "Bollocks!".

2) Now, I agree with both POLLY's and BOB's explanations
of "gallopin' bollockitis" but it can also have an alternate/additional interpretation("double meaning"/"duple-entendre", if you will)...
MyHoney(bless his loving heart), *is* a Ramblin' Rover(we both are and we seem to be coming up to the later mile-markers quite aptly described in the last verse of Ramblin' Rover faster than we're willing to admit to ourselves, lol). He's also a VERBAL Rambler. AND he's been known to embellish his tales of yore("man"- measures? strictly for entertainment purposes? Who knows?/Who cares? His listeners enjoy it & that's what matters). So, yeah, I submit he qualifies as "having gallopin' bollockitis".

I've cobbled this bit out in a hurry. 'Hope I've been clear enough. Comments welcome(particularly "constructive" ones).

Love this song. Having lived a (So-Called)Life more Grasshopper* than Ant, it's kinda biographical, lol [*I'm a fiddler to boot, eh?]. First heard/learnt/performed it with one of my earlier bands[Nod to (The)SpleenBishops; Jim MAXWELL, Brent SANTIN et al -- Hugs&Kisses for you, too, John BISHOP]. Have been waxing "semi-mental" with nostalgia lately and just happened on this site.]

Tacet4now. ~=)charlie